Groups comparison

Emulated on MAME (Multiple Arcade Machine Emulator) - 1971 to 2016
An Arcade games emulator available for almost any platform. (clones and bootlegs are merged to the parent)

DOS 1.x - 1973 to 2014
Requires DOS 1.0 or newer.

License change - 1980 to 2019
The license by which the game is available has changed since release, such as formerly commercial game becoming freeware or open source, or formerly free game becoming commercial/proprietary.

DOS 2.x - 1981 to 2014
Requires DOS 2.0 or newer.

Simple DirectMedia Layer (SDL) - 1989 to 2021
A cross-platform multimedia library designed to provide low level access to audio, keyboard, mouse, joystick, 3D hardware via OpenGL, and 2D video framebuffer.

OpenAL (OAL;Open Audio Library) - 1997 to 2021
Cross-platform audio API for multichannel 3D positional audio originally by Loki Software.

Qt framework - 1997 to 2015
A cross-platform application framework originally by Trolltech.

SDL_mixer - 1998 to 2012
Uses SDL's very basic audio API for sound.

License-postfreedom - 2000 to 2010
Released under a Free or Open Source license but later became proprietary. Any current copyright holder can do this to a FSF/OSI licensed code.